





LIBRARY OF CONGRESS, 



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Shelf ..Hi^- 



UNITED STATES OF AMERICA. 
























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W- 
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CAR LUBRICATION. 



W. E;%ALL, B.S., M.E. 






SECOND EDITION, REVISED. 
FIRST THOUSAND. 




-^s:,^i)^i:^^ ri,' 



NEW YORK : 

JOHN WILEY & SONS. 

London : CHAPMAN & HALL, Limited. 

T895. 



f^ 






Copyright, 189s, 

BY 

JOHN WILEY & SONS. 




BOBEPT DRUMMOND. ELECTROTYPER AJJP PRINTER, NEW YORIf, 



PREFACE. 



Some years ago the subject of car lubrication became 
one of much interest to the writer, and, when attempt- 
ing to acquaint himself with the laws influencing suc- 
cessful practice, he was surprised to find how very little 
information, either of a theoretical or practical nature, 
could be obtained. The accompanying pages are not 
presented as a solution of the question, or as contain- 
ing any important original research, but rather in the 
hope that some of the knotty problems which were 
then presented for solution may be made clearer. 

The laws of friction, as accepted until recently, have 
by later experiments been limited in their application, 
if not confined entirely, to solids in contact. It is at 
least certain that they will not apply in any way as the 
laws governing the friction of solids separated by a 
lubricant. Prof. Thurston's " Friction and Lost Work," 
and the experiments of Mr. Woodbury with those of 
Mr. Tower, are quoted, and several others to a limited 
extent — to whom, it is hoped, proper credit has been 
given. 

It is desired that these few words may stimulate 
further thought, and in that way result in a more satis- 
factory solution of the problem. 

The Author. 

Altoona Machine Shops, May, 1891, 



PREFACE TO SECOND EDITION. 



Since the first edition of " Car Lubrication " was pub- 
lished the subject has received some attention by the 
railroads, as will be noted by the " Report of the 
Committee on Lubrication of Cars," contained in the 
Proceedings of the Master Car-Builders for 1894, and 
the article of Dr. Dudley and Mr. Pease in the Febru- 
ary number of The Railroad and Engineering Journal, 
1892, all of which confirms the conclusions that had 
been reached by the investigations of the author and 
set forth in the first edition. The subject, however, 
has not, by any means, received the consideration it 
deserves. 

Attention is drawn to the continual drift towards the 
softer metals, and it now looks as though a com- 
paratively hard white metal in shells of iron or hard 
brass would be finally adopted as the best bearing 
metal. 

In the second edition a number of typographical 
errors that accidentally appeared in the first edition 
have been corrected. 

The Author. 

May, 1895. 



CAR LUBRICATION. 



CHAPTER I. 

INTRODUCTION. 

In taking up the study of the subject of car lubrica- 
tion we shall find it necessary to consider the features 
in the construction of the car-box and the proportion 
of the different parts, in addition to the care that 
should be given to lubrication, so that the journal will 
be properly supplied with oil and kept in a well-lubri- 
cated condition. While there is no reason why it 
should be so, yet it is a fact that there is probably no 
other branch of railroad engineering that has been so 
dependent upon empirical laws and where the prac- 
tice has been at such variance with the heretofore ac- 
cepted laws governing it. 

The widely taught law that friction is independent 
of the extent of surface in contact, but varies only with 
the pressure, is about ready to be placed among the 
archives of ancient scientists. The pressure inferred in 
this relationship is that exerted over the whole surface, 
and not per square inch — that is, a surface one square 
foot in area under a pressure of one pound per square 
inch would require the same force to move it over a 
resisting surface as it would if made one square inch in 
area under a pressure of 144 pounds per square inch. 

I 



2 CAI? LUBRICATION. 

The extent of surface in contact was supposed to have 
no effect upon the force or work of friction necessary 
to move one body upon another, and consequently 
required no increased effort to produce motion, pro- 
vided the same total pressure was exerted although the 
area of the surfaces in contact might be at variance. 

Recent experiments made with various grades of 
lubricants, to determine the coefficient of friction of 
lubricated surfaces under varying conditions, prove 
conclusively that the amount of surface in contact 
materially influences the work of friction. If the rela- 
tionship of the/' resistance of friction as independent 
of the area of surfaces in contact, but dependent upon 
the pressure," were true, the temptation would be to 
reduce the work of friction and the abrasion of the 
materials by increasing the area of the surfaces in con- 
tact, which would allow the use of a lighter oil by re- 
ducing the pressure per square inch without increasing 
the abrasion. Practical demonstration, however, has 
proven the necessity of avoiding long journals, and, 
with the friction of rotation, an increase in the diameter 
of the journal means a corresponding increase in the 
work of friction. 

While recent investigations have not by any means 
furnished data that enable the subject of car lubrica- 
tion to be reduced to the desired degree of efficiency, 
they give information that is of much value for guid- 
ance in the design, construction, and management of 
lubricated surfaces, and results that will be found to 
accord quite closely with those obtained from practice. 
They indicate, and quite conclusively, that when the 
rubbing surfaces are kept well separated by the lubri- 



IN TROD UCTION. 3 

cant the friction is more dependent upon the nature 
and fluidity of the lubricant than upon the nature of 
the sohds carrying the load. 

There seems to be a combined friction consisting of 
that inherent in the particles forming the lubricant and 
of the moving surface in contact with it. With con- 
stant pressure and temperature, it is dependent upon 
the extent of surface in contact and varies directly 
with it. It is also influenced by the unit pressure, and 
varies in some ratio with the change in the load, but 
not in the same ratio as had been previously supposed. 

As the resistance of lubricated surfaces is made up 
of the resistance of the particles of the lubricant, it is 
evident that any influence that will change the fluidity 
or density of the lubricant will also affect the frictional 
resistance. 

Increase of temperature, increasing the fluidity, 
causes a decrease in the coefficient of friction ; while 
increase in unit pressure causes an increase in the den- 
sity of the fluid, and, necessarily, an increase in the 
friction when motion is produced. 

The ideal condition of lubrication is attained when 
the viscosity of the lubricant at the working tem- 
perature is sufficient, and no more, to keep the surfaces 
of the solids apart under the maximum pressure they 
may have to sustain. 

We should always bear in mind that frictional resist- 
ance and the abrasion of the surfaces represents an ex- 
penditure of money, and, in the aggregate, is of greater 
moment than is generally supposed. 

The subject will be treated in the following chapters 
by taking up the different parts in detail and then con- 



4 CAR LUBRICATION. 

sidering the relationship that must exist to give the 
most economical results. 

It will be considered under the two following general 
heads* 

1st. The proportions and materials that are required 
to meet the demands of the service. 

2d. The most economical way in which these may 
be applied. 



THEORETICAL RELATIONS. 



CHAPTER II. 

THEORETICAL RELATIONS. 

The resistance of friction in car lubrication is that 
which is generally known as "sliding friction of rota- 
tion." It is similar to linear motion, but, as it is an 
arc of contact, it differs in the distribution of the load 
per unit of surface. 

When the bearing is first placed upon the journal the 
arc of contact is small, and it is only after wear has 
taken place that the whole arc included within the 
bearing is in contact with the journal. The amount of 
wear which is necessary to produce this condition is 
comparatively small unless the radius of the bearing 
is made much larger than that of the journal, which 
must be classed as bad practice. 

It will be found that the larger part of the pressure 
is taken at the top of the journal, and decreases in a 
determinable ratio from that point to the horizontal 
axis through the centre of the journal. The work of 
friction is then but a question of the space which is 
passed over against the frictional resistance which is 
offered to the rotation. The space in this case is a 
function of the circumference, and varies as the diam- 
eter of the journal. 

The law of the distribution of the pressure is as fol- 
lows ; 



• CAE LUBRICATION. 

Let (see Fig. i) 

P z=. vertical pressure on unit surface ; 
P^ =. pressure in a radial direction on unit surface ; 
R = radius of the journal ; 

GO = angle made by the radius from a point O with a 
vertical line through the centre of the journal ; 
/= length of bearing; 
L = total load carried. 



For any point, O, 



P. = P cos a). 




The pressure upon a surface Rdo) is 
PJRdao. 



THEORETICAL RELATIONS. 7 

The summation of the pressure should be for an 
equal arc on each side of the vertical, or 

L= r PJRdoo ; 

and by inserting the value of PJ 

^— j PIR cos GO doD, 

From this, the load carried by various subtended arcs 
can readily be obtained. The accompanying table in- 
dicates the relative loads for several values of oo. 



Value of 

(0 


Average pres- 
sure carried 
per square 
inch. 


Square inches 
of surface 
when radius 
equal unity. 


Percentage car- 
ried by the 
first 10° of 
the arc. 


IO° 
20° 
30° 
40° 

50° 


0.34729 
0.68404 
I. 00000 

1.28558 
1.53209 


0.1745 
0,3490 

0.5235 
0.6980 
0.8725 


100.00 

50.78 

34-73 
27.01 
22.67 



It is then evident that a higher percentage of the 
pressure is taken by a small arc of the journal, and that 
the lower surface of the arc of contact is the least im- 
portant part of the distributing surface. It will be 
noticed, too, that as regards the distribution of the 
load there is no serious objection to giving the bearings 
a surface contact that is less than the width of the 
bearing, for instance a width of bearing surface of 
three (3) inches on a journal of four inches diameter. 
It also follows that the practice of boring out the bear- 
ing to a greater radius than the journal is open to no 
serious objection, but, on the other hand, must be done 
to prevent the bearing seizing the journal, providing 



CAR LUBRICATION. 



the difference in the radii is not made too great. 
When this difference is excessive a condition is ob- 
tained similar to that shown in Fig. 2, which will result 
in very poor lubrication and likely produce a heated 
journal, the sharp corners at A having a tendency to 
scrape the oil from the journal. This effect will be 
made more apparent further on. In practice it is found 
that the best results are obtained when the radius to 




Fig. 2. 



which the bearing is bored is about one thirty-second 
(sV) ^^ ^" hyoh greater than the radius of the journal. 
This gives a safe working margin for a new bearing 
and journal, and yet does not give too great a difference 
or opening at the sides of the bearing when a new one 
is placed on a journal that is worn to the minimum di- 
ameter. In cases where journals of different diameters^ 
are used bearings corresponding to these different sizes 
should be kept on hand. In any case the possibility of 
any heating of the journal on this score can be obvi- 
ated by using the lead-lined bearings. 



THEORETICAL RELATIONS. 9 

Before stating the elements determining the work of 
friction, it is necessary to review in a general way the 
results of recent experiments which were made to de- 
termine the laws governing the resistance to motion of 
bodies when separated by a lubricant. Reference is 
made particularly to the experiments by Woodbury 
and Tower, the results from both of which, while under 
different conditions, are corroborative. Those by 
Woodbury were made with low pressures, and the 
curves obtained from his results give a relationship of 
pressure and coefficient of friction, as shown in the 
diagram, marked as Fig. 3. They show conclusively 
that frictional resistance, with an intervening lubricant, 
is not a direct ratio factor of the pressure, as it is with 
unlubricated surfaces ; but, on the contrary, the laws 
seem to follow those of fluid friction more closely 
than those of solids. The result produced by the mo- 
tion of two solids underpressure is a more or less rapid 
abrasion of the metals in contact. With a lubricant 
interposed the conditions are quite changed, and follow 
more closely the resistance which the fluid would offer 
by its own friction. Whether or no this be a motion 
of the particles of the lubricant or of the solid upon 
the surface of the fluid does not concern us. The impor- 
tant consideration is the extent of surface in contact 
which should enter as an element in the calculation of 
the work done. The best way for our purpose is to ob- 
tain the frictional resistance of the lubricant at the 
pressure carried, reduced to the resistance under these 
conditions for a unit surface. The resistance of friction 
would then consist of two elements : the coefficient of 
friction per unit of surface for the working pressure 



10 CAR LUBRICATION. 

and temperature, and the number of units of surface 
in contact. Representing these by/" and a respectively, 
would give as the relationship of the total work of fric- 
tion 

W = f.a.p . 27tR X n, 
where 

n = number of revolutions per unit of time ; 

/f = pressure per square inch. 

With given pressure and temperature the minimum 
value of the function/", a is determinable. 

First, the pressure on the journal and the tempera- 
ture attained under the maximum speed will indicate 
the density of the lubricant which it is necessary to use 
to prevent the surfaces coming in contact, and in the 
case of car lubrication will vary with the seasons of the 
year, causing a grading of the oils into those for sum- 
mer, and lighter ones for winter use. Second, the 
value of a will depend npon the available space allowed 
for the journal. It will be seen further on that the 
results of the experiments indicate that the most 
economical conditions are obtained by increasing the 
area, within practical limits, and using a correspond- 
ingly lighter body oil for the lubricant. 

The value of a for the most economical results is 
where any further decrease in the resistance by the use 
of a more fluid oil is counteracted by the increased 
resistance resulting from the larger surface in contact. 
More explicitly the experimental results indicate that, 
within practical limits, a lubricant of greater fluidity 
and correspondingly lower coefficient of friction can be 
used by increasing the area, and in that way reducing 
the unit pressure until the limits are exceeded, when 



THEORETICAL RELATIONS. II 

any further increase of the contact surfaces produces a 
reverse effect. It will be remembered we found that 
the additional surface obtained by increasing the arc of 
contact does not produce a proportionate decrease in 
the pressure per unit of surface, so that the oil that is 
selected for the purpose must depend upon the pres- 
sure that exists at the top of the bearing. Practically, 
an arc of contact of some magnitude is necessary for 
strength and stability, and to give a fairly large area to 
accommodate for the abrasion which also takes place. 
Any increase beyond this arc is economical only so 
long as the increased surface decreases the pressure 
carried at the centre of the arc to an extent that the 
lighter oil will, by the consequent reduction in the co- 
efficient of friction, overbalance the increased resistance 
produced by a greater area. Assuming c as the con- 
stant and necessary arc of contact and w as the desired 
angle, it is not economical to increase go when the ex- 
pression 



is greater than 



/—- X 6.282. 
360 

/'4-x 6.282. 

360 



/and/' indicate the coefficients of friction per unit of 
area for the lubricant which must be used to overcome 
the maximum pressure existing in the two cases which, 
in one sense, measures the fluidity of the lubricant. 
This is on the basis of the diameter and length of the 
journal remaining constant. 

An increase in the length of the journal seems to be 
advantageous, provided it is not carried beyond the 



12 CAR LUBRICATION. 

limits placed upon it by practice. The diameter of the 
journal is dependent upon its length and the load to be 
carried. Taking the usual expression for a beam sup- 
ported at one end and uniformly loaded, we have 

_ TTtR' 

U 

where T ^= safe ultimate load for the metal, and the 
other symbols indicate the same as in previous formulae. 
For the deflection we have 



27tR'' 

where d represents the deflection. All are indicated in 
pounds and inches. 

The formula for the variation of the diameter for 
changes in the length will be used again. 



COEFFICIENT OF FRICTION: 13 



CHAPTER III. 

COEFFICIENT OF FRICTION. 

With the exception of the method of lubrication, 
there is no other element in connection with the sub- 
ject under consideration that has received more atten- 
tion than that of the coefificient of friction, and yet 
there is no other that is in as crude and indeterminable 
a state. As investigation progresses, the subject seems 
surrounded with more and more variables of a com- 
plicated nature, which indicate the importance, if not 
necessity, of the utmost care when the best results 
from lubrication are desired. 

The latest study of the subject has brought out some 
very interesting results, and has conclusively shown 
that it is now necessary to at least limit the old laws of 
friction to dry surfaces in contact, if not exclude them 
totally. The resistance of friction, when a medium is 
introduced between the so-called rubbing surfaces, fol- 
lows laws quite different and more intricate than those 
determined by Morin, which were to the effect that 
" friction was independent of the surface in contact, 
but directly dependent upon the pressure keeping the 
surfaces together." 

Where friction is produced it is important to distin 
guish between the two conditions to which the two sets 
of laws apply ; in one it is a solid against a solid, the 
particles of each interlapping and causing resistance by 



14 CAR LUBRICATION'. 

the efforts of the particles of one metal to tear away 
those of the other. Where lubrication is introduced it 
is intended that the two solids shall be separated by a 
film of the lubricant, generally a liquid. In this latter 
case the resistance assumes the nature of the laws of 
fluids, and consists of the friction of the particles of the 
lubricant and that of the solid against the fluid, form- 
ing a combined resistance, the percentage of each to 
the whole retardation depending upon the nature of the 
lubricant and the metal surfaces. As long as the 
metals are prevented by the lubricant from coming in 
contact, it is found that the friction is dependent upon 
the fluidity of the lubricant, and varies with changes of 
this fluid condition, decreasing with a higher tempera- 
ture and increasing with a less degree of heat. 

We will assume, first, that the lubricant prevents any 
contact of the metal surfaces. The condition then 
stands between the laws of solid friction on the one 
hand — that is, independent of the surfaces in contact, 
but dependent upon the total pressure, — and the laws 
of friction of liquids on the other, where it is inde- 
pendent of the pressure per unit of surface, but is 
directly dependent upon the area and increases as the 
square of the velocity. From most recent investigation 
this intermediate condition has been found to be, when 
stated in a general way, that the coefficient of friction 
decreases with an increase of the pressure, although the 
total resistance rises directly but not proportionately 
with the higher unit pressures and increases with the 
velocity, although not as rapidly as its square. It is 
also found to be dependent upon the extent of surface 
in contact. An exact relation between these varying 



Coefficient of FRictioht. i^ 

conditions has not yet been obtained, evidently because 
they vary so materially with any slight variation in the 
method used of lubricating the surfaces. As, for in- 
stance, when the oil-bath is used the laws of lubricated 
surfaces, especially as regards surface and pressure, fol- 
low those of liquid friction very closely ; while with 
less efficient means of lubrication the results show a 
condition between solid and liquid friction. This mat- 
ter will be brought out more prominently in the chap- 
ter on the methods of lubrication. 

With the surfaces in good condition and the oil-bath 
method of supplying the oil, which may be considered 
as practically perfect lubrication, it was found that the 
mean resistance per square inch of surface, with pres- 
sures varying from lOO to 310 pounds per square inch, 
was as follows : 

Lubricant. Mean resistance in pounds. 

Sperm-oil 0.484 

Rape-oil 0.5^2 

Mineral-oil... 0.623 

Lard-oil 0.652 

Olive-oil 0.654 

Mineral grease 1.048 

[Results obtained by Tower. — See Engineering for November 16, 
1883, and Feb. 6, 1885.] 

The speed was 300 revolutions per minute, and jour- 
nal four inches diameter and six inches long, while the 
temperature was maintained at 90° Fahrenheit. 

A constant temperature is essential for a proper com- 
parison, for in one case the coefficient of friction of lard 
oil decreased to one third (^) its value at 60° by increas- 
ing the temperature of the lubricant to 120° Fahren- 
heit. 



l6 CAR LUBRICATION. 

Probably the most accurate laboratory experiments 
that have been conducted for the determination of the 
resistance of lubricating oils were those made by 
Woodbury for the North-Eastern Cotton Manufac- 
turers' Association, as published in their proceedings of 
April 28, 1880, and in the proceedings of the American 
Society of Mechanical Engineers, as contained in 
volume VI. They were made with the object of ap- 
propriating the results to cotton and woollen machinery 
where low pressures are used, and to that extent are 
not well adapted to the lubrication of car journals ex- 
cepting as showing the action of lubricants under vary- 
ing conditions of temperature and a limited range of 
pressure. They were presented about the same time 
as the results of Mr. Tower's experiments, the latter, 
however, under heavier pressures, but both clearly 
showing the different conditions under which friction 
must be studied when solid surfaces are lubricated by 
such bodies as the mineral and animal oils. It was 
found in the tests that uniform results could not be 
looked for unless constant temperature, velocity, press- 
ure, area of surface in contact, and thickness of the 
film of the oil between the surfaces were maintained, 
the latter depending somewhat upon the method of lu- 
brication, the results indicating clearly that the resist- 
ance of friction was dependent upon and changed with 
a variation in any of the above conditions. The 
metallic surfaces were cast iron and bronze, the latter 
composed of copper 32, tin 2, lead 2, and zinc I. In 
one case all conditions were kept constant excepting 
that of pressure, the diagram represented as Fig. 3 in- 
dicating a decrease in the coefficient of friction, with 



COEFFICIENT OF FRICTION. 



17 



increased pressure per unit of surface, but an increase 
of total resistance. Similar tests were made, keeping 
the pressure constant and varying the temperature, 
which gave the eJEfect of the variation of the tem- 
perature upon the coefficient of friction. 

The two diagrams, Figs. 3 and 4, indicate by the two 
curves the variation which takes place in the coefficient 
of friction under the conditions named. 

In Fig. 4 it will be noticed that the variation in the 







1 


Coefficient 


130 
-110 

poo 

1 90 

ig 80 

70 


\ 


\ 


















\ 


\ 


Te 
of 


nperat 
Frictio 


andC 
i.varyi 


oefficii 


at 








ProBaviie and 




\ 


\" 


pom 


lonatau 
da per 


t=2a 
iquare 


ad 6 
nch 






1 












\ 


\ 










.ao 




\ 




Is 


OfF 
mperal 


oie.coi 


slant =100 F. 




g'4 




-\ 


I 










\ 




\ 








1 






\ 












\ 


\ 








.s2 
£ 

r 






\ 


\ 


V 












\ 














■ 










\ 




i 











10 . 

c 


JO . 
oef. of 


30 .'■ 
Friction 


10 . 

If 


50 




( 


.1 


c 


:i 

oot-of 


U .4 
Frictio 


.b 
1. 








Fig. 3. 



Fig. 4. 



coefficient of friction due to changes in temperature 
follows closely the laws of the straight line, indicating 
a proportionate decrease with the increase in tempera- 
ture ; the angle of the line with the abscissae depending 
upon the pressure per square inch. 

Combining these two diagrams gives a curve, as 
shown in Fig. 5, for a coefficient of friction where the 
two elements, pressure and temperature, vary ; and it is 
this relationship which most concerns the lubrication of 
surfaces such as car journals, as in this case the tern- 



lo CAR LUBRICATION^ 

perature is subject to variations arising from changes 
of seasons and weather, while the pressure carried per 
square inch is dependent upon how long the bearing 
has been subjected to wear and attrition, the unit press- 
sure decreasing with increase of service. While the 
results obtained by Woodbury are the most accurate 
that have been published and probably ever made, both 
as regards design of apparatus as well as its manipu- 
lation, there still lacks sufficient uniformity for the 
derivation of a definite law as to the variation of fric- 
tion with changes in temperature and pressure. For 
instance, the decrease in the coefficient of friction for 
pressures of from one (i) to five (5) pounds per square 
inch is as follows: 



Pressure 
per square 

inch. 
Pounds. 


Coefficient of 
Friction. 


Decrease in 

Coefficient of 

Friction, 


Difference in 

the amount of 

decrease. 


I 
2 
3 

4 
5 


0.3818 
0.2686 
O.2171 
0.1849 
0.1743 


0.0000 
O.II32 
0.0515 
0.0322 
0.0106 


0.0000 
0.0000 
0.0617 
0.0193 
0.0216 



The decrease in the coefficient of friction from an in- 
crease of pressure of one (i) to two (2) pounds was 
0.0617 more than that from two (2) to three (3) pounds, 
while the increase from three (3) to four (4) pounds was 
0.0193, and nearly the same as took place when the 
pressure was increased from four (4) to five (5) pounds. 
The above is cited more to prevent a deduction of 
too wide a nature rather than to deter from the grati- 
tude which the engineering profession must feel for 
the derivation of the general law of the variation of 



COEFFICIENT OF FRICTION. 



19 



friction with lubricated surfaces when the temperature 
and pressure are varied. The care which it was neces- 
sary for Mr. Woodbury to exercise to obtain these 
results can be appreciated when it was found essential 
to run the apparatus, using gasoline or its equivalent, 
to clean an oil from the surfaces after testing. It re- 
quired a travel of one surface over the other equivalent 




12 3 4 5 

•Fxesaure per sc^uare-inoh. 

Fig. 5. 

Note. — The coefBcient of friction in the three cases is represented 
in actual pounds resistance. 

to about forty (40) miles before it was advisable to 
commence the trial of the succeeding oil, and even then 
indications could be noticed in the test following of 
the properties of the oil previously tried. This is con- 
sidered further evidence that the friction of lubricated 
surfaces is made up of the friction of the fluid, and 
tends to prove that the lubricant imbeds itself into 
the surface of the metal, producing a fluid resistance 
rather than a resistance due to the rubbing of the sur- 
face of the metal upon the surface of the lubricant. 
This effect will be taken up again in the chapter on 
Bearing Metals, 



20 CAR LUBRICATION. 

The variation in the coefficient of friction with 
changes of temperature can readily be carried to an 
extreme, as it has been found that while the resistance 
decreases as the temperature is raised, there is a point, 
depending upon the unit pressure and viscosity of the 
lubricant, where the coefficient starts to increase very 
rapidly with increase of temperature. The same holds 
true with a variation in the pressure ; and while the laws 
of changes are true as stated, in a general way, they 
depend and are limited by the viscosity of the lubri- 
cant used, and also the pressure which it is necessary to 
carry. The rapid increase, when the limits of tem- 
perature and pressure are exceeded, is due to the solids 
coming in contact and causing increased friction by the 
abrasion of the surfaces, reducing the condition from 
friction of fluids to that of solids. 

An attempt has been made to prove a positive rela- 
tionship between the viscosity of an oil and its coeffi- 
cient of friction ; and while they are, no doubt, more or 
less dependent, there is hardly sufficient data at hand 
to resolve this to a definite basis. In addition to that 
of viscosity lubricants possess a property designated as 
unctuousness, which seems to influence the coefficient 
of friction as much, if not more, than the viscosity. It 
appears, and there seems sufficient information at hand 
to anticipate it, that a relationship of a positive and 
determinable nature between the three elements, co- 
efficient of friction, viscosity, and unction, is obtainable. 

The results of the experiments made by Mr. Tower, 
as presented before the British Institute of Mechanical 
Engineers, are of such a nature that they can readily 
be converted into practice with a resulting profitable 



C0EFFICIEN7' OF FRICTION. 21 

application. They go to corroborate, to a close degree, 
the results of Mr. Woodbury, although they have the 
advantage of having been made with higher pressures. 
It should be remembered that with high pressures, 
such as those obtained before seizure takes place, the 
film of oil separating the bearing and journal has been 
found to be very thin, and shows the result that maybe 
expected where the irregularities or projections on the 
surface of the bearing are greater than the thickness 
of the film of oil used to separate them, producing 
when in motion a rapid and detrimental abrasion of the 
metals with a marked increase in the friction. It would 
not be safe to allow the irregularities to project from 
the surface more than the thickness of the film of oil, 
unless, of course, the prevailing area is of this height. 
The other extreme, of having the surfaces too highly 
polished, must also be avoided, as it has been found 
that a moderately rough machined surface will carry 
something like seven (7) times more pressure before 
seizing than can be obtained from highly polished sur- 
faces. The proper condition would seem to be about 
that produced by a boring tool, except with the soft 
metals, which, from their-nature, are incapable of tak- 
ing a high polish. 

For the purpose of comparison let us consider 
briefly some of the results obtained by Mr. Tower where 
the journal was lubricated by the oil-bath method and 
the surfaces were in good condition. Assuming a 
loaded car of total weight of 80,000 pounds would give 
10.000 pounds per journal. At a pressure of 300 
pounds per square inch this would require a bearing 
area of 33.33 square inches to carry the load. With 



22 CAR LUBRICATION. 

the resistance given for mineral oil of 0.623 pounds per 
square inch on a journal 4 inches in diameter and a 
wheel 33 inches in diameter, a tractive resistance of 2.52 
pounds per journal, or of 0.504 pounds per ton, would 
be required after motion had been produced. With 
the latest dynamometer readings the resistance of 
journal friction for loaded cars will probably reach as 
low a figure as 2 pounds per ton on level tangent when 
running at a speed of 15 miles per hour. Retracing, 
this figure gives a journal resistance of 82.5 pounds, and 
as high a figure as 2.48 pounds per square inch of bear- 
ing contact. It will be seen how low an efficiency is 
obtained in practice, but it should be remembered that 
the above laboratory tests were with the oil-bath 
method of lubrication, which has proven, when so tried, 
to be far superior to any other method that is at pres- 
ent known for lubricating surfaces. In most cases it 
has been found that the resistance of friction is a direct 
proportionate function of the area of surfaces in con- 
tact ; twice the bearing surface, all other conditions 
remaining the same, will give, approximately, twice the 
resistance from friction. 

The information as presented by the theoretical tests 
of oils is of much importance in the selection of the 
one best suited for the conditions of any particular 
service. In car lubrication, however, a constant rela- 
tionship between bearing surface, lubrication, tempera- 
ture, and pressure does not exist, and for that reason a 
large factor of safety must be used to cover the varia- 
tions and the extreme conditions that exist in practice. 
For instance, when starting with a new bearing, the 
surface in contact is much less than when it has wori) 



COEFFICIENT OF FRICTION. 23 

down to a point where the whole arc of the bearing 
comes in contact with the journal. This is one of the 
conditions which must be met, for with the irregularities 
of the parts accompanying the distribution of the load 
it is found, excepting with the so-called soft-bearing 
metals, that heating will almost invariably result if the 
bearing is fitted to the journal throughout the whole 
arc which it is capable of including. There seems to 
be a binding action on the journal. If the bearing is so 
fitted as to allow a small amount of motion of the 
bearing on the journal, the wear will take place in a 
manner consistent with the alignment of the journal- 
box. The variation in the unit pressure is not, how- 
ever, as wide as would at first be supposed, as will be 
seen on reference to Chapter II, where the variation in 
unit pressure due to changes in arc of contact is given. 
The viscosity of the oil selected should, then, be such 
that it will keep the surfaces apart under the conditions 
of minimum arc of contact, and at the highest tem- 
perature that will be met. This temperature is not de- 
pendent altogether upon that of the atmosphere, but, 
on the contrary, will vary much with the nature of 
the service. For instance, with long continuous fast 
runs the temperature of the journal will be consider- 
ably above that of the atmosphere. With this service 
the heat arising from the work of friction will be such 
as to raise the temperature of the journal and bearing 
before a constant condition is reached, and the conduc- 
tivity and radiation of the heat through and from the 
surfaces is not sufficiently rapid to accommodate for 
all the heat generated, and keep the temperature down 
to that of the atmosphere. It will not be found un- 



24 CAR LUBRICATION. 

common for journals in severe service to reach a tem- 
perature of a hundred and fifteen (115) degrees Fahr. 
with the atmosphere only 50 to 60 degrees. This 
results in better lubrication, provided an oil has been 
selected with sufificient body to meet the conditions. 
If such is not used, the parts are reduced to such a sen- 
sitive state that the slightest cutting from the entrance 
of foreign matter between the bearing surfaces is apt to 
result in an overheated journal, or what is generally 
known as a hot box. The. maximum presure per 
square inch that must be sustained without seizure at 
the highest temperature that will be reached will deter- 
mine the grade of the oil which it will be necessary to 
use. The resistance is a minimum when the product of 
the coefficient of friction and the area in contact is a 
minimum. When the limitations of the case require 
the use of high unit pressures, correspondingly heavier 
oils must be used to prevent the bearing seizing the 
journal ; but that oil, all other variables remaining the 
same, which will give the lowest coefficient of friction 
and prevent the surfaces coming in contact is the one 
to be used. 

The work done is dependent upon the circumference 
of the journal, so that any change in its diameter af- 
fects correspondingly the work of friction. The diam- 
eter of the journal varies closely as 1/ l^. The work 
of friction is dependent upon the coefficient of friction 
per unit of surface, the area in contact, and the distance 
travelled ; or, depends upon 

W=^7tafnWT,, 

Assuming a constant deflection, the variation in the 



COEFFICIJSJVT OF FRICTiON'. 2$ 

diameter is that necessary to maintain strength for the 
changes in the length. By referring to the table on 
page 15 it will be seen that we can determine the in- 
trinsic values of the heavy and light oils on the basis of 
the work of friction, resulting from the resistance which 
each offers to motion. For instance, Tower found that 
with rape-seed oil the pressure which it would resist up 
to the point of seizure was 573 pounds, and with min- 
eral oil a pressure of 625 pounds per square inch. To 
make a comparison between sperm oil, which is of still 
lighter body, and mineral oil we would have, assuming 
a proportionate power of resisting pressure, 541 pounds 
pressure as the capacity of the sperm oil. Taking this 
oil, and with a bearing surface of 1^ by 8 inches, we 

- , ., , , . f . , ., li X 8 625 

find it would require for mineral oil = — ~ or 

X 540 

10.4 square inches of surface to sustain the load. The 

corresponding length would be 6.9 against 8 inches 

with sperm. The expressions for the work of friction 

in the two cases would be 

W = Ttafn \/X', 
W, = na'f'n VJJ-, 
and their ratio 

fa' f // 

Sperm oil =/ = 0.484, a =. \2, /, = 8 ; 

Mineral oil =/' = 0.623, a' = 10.4, //= 6.9 ; 

112.73 

r = = o.Qii. 

123.75 



26 CAJ? LUBRlCATiOl^. 

While some of the figures are approximate only, they 
are sufficiently close to show that the heavy oils, even 
with the decrease of bearing surface which they allow 
are not as economical as the lighter ones, so that it 
may be stated in a general way that the work of fric- 
tion is least where the conditions are such that they 
will allow an increase in the length of journal, result- 
ing in an increase of the bearing surface under the 
same load, when an oil of lighter body may be used. 

This conclusion has, of course, its practical limits, and 
it would probably require modifTcation if experiments 
of a more detailed nature were made on the same lines 
as started by Mr. Tower, but would not, in all proba- 
bility, change the general result. It clearly shows the 
importance and value which must be attached to fur- 
ther investigation in this direction. 



BEARING METALS. 2 J 



CHAPTER IV. 

BEARING METALS. 

Oil and bearing metal, in their relation and applica- 
tion to car lubrication, are capable of almost unlimited 
treatment, so much so that it has now become the work 
of a specialist to properly follow each and advise as to 
their efficiency. The easy adulteration of oils make 
them a subject of suspicion and necessitate rigid speci- 
fications and inspection to eliminate the chance of such 
deterioration. This having been successfully accom- 
plished, through proper specification and rigid inspec- 
tion, the next point is the selection of the oil best 
suited for the journals to be lubricated. This requires 
the consideration of properties, in addition to the co- 
efficient of friction. Those referred to are the rate of 
evaporation at the working temperature, the tendency 
of spontaneous combustion from the evaporation, the 
decomposition of the oil by the atmosphere, and, still 
further, that of the chemical action of the acid, which 
animal and vegetable oils contain to a greater or less 
extent, on the metal used for the bearing. 

For instance, an oil, whose exposed surface gave an 
evaporation of 20 per cent would be far inferior to one 
which gave but 10 per cent evaporation at the same 
temperature and in the same time. It is also objec- 
tionable on the ground that the oil giving the higher 



28 CAR LUBRICATION. 

evaporation would also be more liable to give trouble 
from combustion arising from the rapidly vaporized oil. 
Care must be taken not to conflict the flashing point 
with the rate of evaporation, as they are not in anyway 
related, for it has been found * that, in one case, two 
oils having the same flashing point gave the rate of 
evaporation of 9.4 and 24.6 per cent respectively. 
When determining the percentage of evaporation of 
oils, the surface, time, and temperature should be the 
same in all cases, as otherwise it would not be a true 
comparison. The mineral oils have a low evaporation, 
and when mixed with those of an animal and vegetable 
nature prevent, to a large extent, the spontaneous 
combustion which is apt to result and give trouble 
when the animal or vegetable oils are used alone. The 
chemical effect arising from exposure to the atmos- 
phere is of much importance in its influence upon the 
lubricating value. This action, with the fine particles 
of dust or foreign matter which enter through the front 
and back of the box, reduces the oil in the top of the 
waste to a pasty condition which materially depreciates 
it as a lubricant. It should be remembered that the 
result obtained by the use of an admixture of the 
mineral and animal oils is dependent upon their relative 
proportions and the temperature to which the mixture 
is subjected. The use of the petroleum products has 
a remarkable effect toward reducing the tendency to 
inflame, so common when the animal and vegetable oils 
are used alone. The relative value of oils on the basis 

* See Prof. Ordway, in Proceedings of Semi-annual Meeting of 
N. E. Cotton Manufacturers' Association, held in Boston Oct, 30, 

1878. 



BEARING METALS. 29 

of percentage of evaporation and inflammability is un- 
known ; in fact, it is as yet an undeveloped field, but 
represents properties which must sooner or later enter 
as factors in the efificiency of an oil for lunricating pur- 
poses. The importance of these will be appreciated 
from the results which Ordway found, where with one 
oil the evaporation in twelve hours, at a temperature 
140 degrees (Fahr.), was 24.6 per cent. 

As well, too, should the question of the chemical ef- 
fect of the acids in the oil be taken into consideration. 
For these two reasons, lower evaporation and freedom 
from acid, the mineral oils are coming into general use 
for car-lubricating purposes, while they also give, from 
their lubricating qualities, as low a coefificient of fric- 
tion as any of the animal or vegetable oils. They can 
be obtained of almost any desired gravity and fire test,- 
and, when clean, are particularly well adapted to the 
service in question. 

The brass-foundry practice of to-day is still so much 
dependent upon empirical laws that it is impossible to 
reach any definite or concise conclusion as to the exact 
nature of the alloy, all things considered, which gives 
the best results for car-bearings. So much depends 
upon the foundry treatment that a chemical analysis 
is of very little value from which to draw any definite 
conclusions as to the nature of the service which a 
known mixture of metals will give. The same ingre- 
dients differently treated will give alloys of marked 
variation in their physical properties, and until the 
foundry working can be reduced to a more accurate 
science we must be subjected to the so-called " kinks " 
which have in some cases produced metals of remark- 



30 CAR LUBRICATION. 

ably good wearing qualities. This is illustrated in 
phosphor bronze, where the metal as produced contains 
about 0.75 per cent of phosphorus, while about one (i) 
per cent is used during the treatment. The effect of 
the phosphorus is to produce a more solid casting by 
reducing the amount of oxidation which takes place 
during the mixing of the metals, but the presence of 
the phosphorus in the metal after melting has no effect 
upon the quality. 

The metals used for bearings may be classed about 
as follows : phosphor bronze, brass, and the so-called 
white metals, the latter containing a large percentage 
of lead, zinc, tin, or antimony, with but little or no 
copper. 

Each has a wide range of hardness, but from all that 
can now be gathered, the white metals give excellent 
service and wear less than the harder alloys. In 1883 
the writer had an excellent opportunity to compare, in 
a general way, the service of a hard bearing with one 
composed of antimony and lead, — the latter material 
was run into an iron shell. The two roads using the 
metals were located in the same part of the country, 
started from the same place, and had the same destina- 
tion ; in fact, they paralleled each other for a large part 
of the distance, so that the service was as nearly alike 
as it is possible to obtain for a comparison. The bronze 
required, on an average, a consumption of oil of 0.945 
of a pound, and the white metal an oil consumption of 
0.3075 pound, each, per car per 100 miles. Where the 
bronze was used it was necessary to resort to lard oil, 
making the cost per car per 100 miles in the two cases 



BEARING METALS. 31 

6.3 and 0.88 cents respectively, nothing but common 
black oil being used with the white metal. 

The white alloy was remarkably free from heating, 
while with the bronze bearings hot journals were giving 
continual annoyance. 

As regards the wear of the soft and hard metals, the 
experience with bearings lined with lead alone indicates 
the remarkably long service which can be obtained 
from even a lining but -^-^ of an inch thick. Experi- 
ments as given in the Railroad Gazette for March 5, 
1886, are much in favor of the white metals. 

There is some difference of opinion as to the resist- 
ance of friction, as well as their effect upon axle wear, 
with the red brass or equally hard-bearing metal, and 
the so-called white metal, but, as far as is known, no 
experiments have been made giving results by which 
a comparison can be drawn to determine the efificiency 
of these two features of the metals. Research with 
this object would be of much value. As regards axle 
wear, however, it will be seen, by reference to the chap- 
ter on the cost of lubrication, that bearing metal and 
axle wear are almost equal in value for the loss result- 
ing from abrasion per 1000 miles. With soft and hard 
metals moving together the result is always a more 
rapid abrasion of the harder one. This is where the 
surfaces are separated by a grinding material ; but when 
properly lubricated the condition is quite different, as 
then the separating material is fluid and slow in its 
wearing action, and, from the experience of those who 
have the white metal in general use, the wear is not in- 
creased by the particles of dust which its opponents 



32 CAR LUBRICAl^ION. 

claim become imbedded in the bearing, and in that way 
exercising an additional grinding action upon the jour- 
nal and increasing the wear over that produced by the 
harder metals. 

While there seems no reason to expect a more rapid 
wear of the journal from the softer metals, yet it is a 
subject seriously affecting the cost of lubrication, and 
one upon which there is lacking sufficient information 
to warrant the positive assertion that the softer metals 
are superior to the harder ones for bearings. Ex- 
perience so far, however, seems to be in favor of the 
white metals. This much can certainly be said that a 
large part of the cost of lubrication of cars where the 
harder bearing metals are used is due to the loss result- 
ing from heated journals, and the white or softer 
metals invariably give less trouble from this cause than 
any other alloy that has yet been made. 

There has been a tendency to attribute the metal con- 
tained in an oil that had been in service solely to the 
wearing of the bearing, but the experiments of Volney 
will show the relative action of different oils upon the 
decomposition of brass. The figures also represent the 
value of the oils in this respect, and, together with the 
oxidation which results from exposure to the atmos- 
phere, indicate the influence which these properties 
have in producing the pasty condition of the waste. 
The dissolving power should be considered in its rel- 
ative importance in the selection of the oil that is to be 
used. It also shows that the bearing metal found in 
the oil of a journal-box is not all due to abrasion. 

Attention is drawn to the low dissolving power of the 
crude petroleum oils, another property that should fa' 



BEARING METALS. 33 

vor the use of these oils for car lubricating purposes. 
On the whole they will maintain a more uniform con- 
dition, and they have fewer detrimental properties than 
oils of either vegetable or animal origin. 

Name of Oil. Relative Dissolving Power. 

Menhaden oil 0.51 1 

Neatsfoot " 0.505 

Olive oil o. 504 

Crude cotton-seed oil. .. ., 0.348 

Lard oil 0.131 

Crude petroleum from Scio 0.000 

Note. — For general results of tests of bearing metals and oils made 
on the Paris-Lyons-Mediterranean Railway, see appendix containing 
translation from Revue Gdn&ale des Chemins de Fer. 



34 CAJi lubrication: 



CHAPTER V. 

METHODS OF LUBRICATION. 

The devices that have been designed and the so- 
called inventions that have been patented to lubricate 
car journals are innumerable, and yet there is not one 
at present in use that can be said to be in such a stage 
of development as to promise superiority over the 
method of using cotton or woollen waste when this is 
properly arranged and manipulated. 

The writer has had experience with numerous de- 
vices, most of which were arranged to lubricate from 
the under side of the journal. The nature of such 
devices was various ; some were made up of a revolving 
cylinder in contact with the under surface of the jour- 
nal, while the lubricating mechanism ran in oil. The 
roller, when such is used, receives its motion from the 
journal in which it is kept in contact by a spring or 
some similar arrangement. Devices of this general na- 
ture have been made in numerous quantities, all differ- 
ing only in some minor detail. None of them have 
been known to produce satisfactory results. Mechani- 
cal methods in the nature of pads kept in contact with 
the journal by springs have been tried, but from a 
thorough test the results seem to indicate that the elas- 
ticity of the waste commonly used is superior to the 
mechanical devices, not only in the quality of the lubri- 
cation, but also in the mileage rendered. One case is 



METHODS OF LUBRICATION. 35 

known where an attempt was made to lubricate by 
feeding oil through the top of the bearing, and by- 
waste at the bottom of the journal, similar to boxes 
used on foreign roads ; and although the trial was of 
short duration, no apparent advantage over the method 
now generally used was noticeable. Devices have also 
been attached to the front of the journal for lifting the 
oil to the bearing, some of which have proven fairly 
satisfactory. In fact, the possible methods of lubri- 
cating car journals are innumerable, but with any 
mechanical device the objection which can be predicted 
with a fair degree of certainty is the annoyance and ex- 
pense that would result from even a small percentage 
of breakages. The number of hot boxes, when figured 
on a percentage basis, is exceedingly small and less, it 
is believed, than can be obtained by any mechanical de- 
vice, however simple its construction may be. We may 
except the so-called roller bearings, which have been 
tried with more or less satisfaction in an experimental 
way. The theoretical advantage arising by resolving 
the friction from that of sliding to that of rolling would 
appear to be a large gain ; and yet from the experiments 
of Wellington (see Proceedings of American Society of 
Civil Engineers) it would appear that this advantage is 
indicated only during starting, but is not so large a per- 
centage gain after the velocity is increased. Roller 
bearings have been known to run successfully for loo,- 
ooo miles, but it is not known that they have been sub- 
jected, by a more general introduction, to an extensive 
trial to determine their mechanical efficiency, such as 
wear and tear, and comparison with sliding friction 
with the surfaces separated by a lubricant. 



36 



CAR LUBRICATION. 



The results of Tower's experiments, previously re- 
ferred to, give a close idea as to what is to be expected 
of the different methods of lubrication. It was found 
with three (3) methods of lubricating journals, feeding 
the oil from below and from above the journal, that 
the following ratios of their efficiencies will result : 



Method. 


Actual Load. 

Pounds per sq. 

inch. 


Coefficient 
of Friction. 


Comparative 
Friction. 


Oil Bath 


262 
252 
272 


0.00139 
0.00980 
O.ocgoo 


1. 00 


Siphon Lubricator 


7.06 
6.48 


Pad under journal 





The siphon lubricator was placed on the top of the 
bearing. The tests were under the same conditions. 
Rape-seed oil used. Journal, 4 inches diameter, run- 
ning at a speed of 150 revolutions per minute. Tem- 
perature 100 degrees (Fahr.). 

There can be no question, then, as to their relative 
efficiencies. The oil-bath rnethod has had numerous 
trials upon car journals, but has always proved a fail- 
ure from the difficulty of obtaining a mechanical means 
that would retain a tight joint at the back of the box 
unless it be made of such a complicated nature as to 
outweigh, on account of repairs, the advantages accru- 
ing from the method. The siphon method has objec- 
tions on account of the high resistance offered, the 
cause for which will appear further on. It can safely 
be concluded that the use of a pad under the journal 
gives a higher resistance than would be obtained with 
what is known as waste, due to the closer texture 
which its name imphes. This gives it less power to 



M&THdDS OF LUBRiCATIOl^. 37 

absorb the oil, the importance of which is evident from 
the high efificiency obtained with the oil-bath method 
of lubrication. Two surfaces that fit tightly wnen 
dry can be made to move easily on one another oy 
interposing a lubricant. It would seem, with the resist- 
ance arising from the tight fit when dry, that the intro- 
duction of additional material between their surfaces 
would offer still more resistance to their motion. The 
application is so common that the reason why it should 
be so is generally lost sight of. With this exceedingly 
thin layer of oil, whether in the nature of globules 
which have penetrated the pores of the metal, or a 
continuous layer of the lubricant between the surfaces, 
the result indicates the strength of the wedging action 
between the metals in contact which enables the lubri- 
cant to be introduced. This is quite the same action as 
when lubricating by means of an absorbent material 
which is saturated with the lubricant and placed in con- 
tact with the lower side of the journal, unless the bear- 
ing grips the journal and scrapes the oil from the sur- 
face, in which case the object is defeated. With journal 
friction, from the nature of the distribution of the 
load, it will be noticed, by referring to Chapter I, that 
the radial pressure of the journal increases from zero, 
when the bearing includes a semicircle, to a maximum 
which is on a vertical line through the centre of the 
journal ; that is to say, the nature of the distribution is 
such as to make the action the same as that of a wedge 
even when the bearing is in contact throughout the 
whole of its arc. It is an increase from a minimum to 
a maximum pressure per unit of surface. The results 
of Tower are practical demonstrations of this effect. 



3S Car LuBRiCATioi^. 

During the progress of the experiments with the oil- 
bath method of lubrication he had occasion to remove 
the bearing. It was then decided to insert a lubricator 
in the top of the bearing, for which a |^-inch hole was 
drilled. After re-starting the experiments and before 
the cups were inserted in the top, oil was observed to 
rise in the hole which had been drilled, and was noticed 
to exude at considerable pressure, which, when indi- 
cated on the guage attached to the top of the bearing, 
was found to be more than 200 pounds per square inch, 
while the average pressure (vertical) upon the bearing 
was 100 pounds per square inch. It was further found, 
when a groove was cut the whole length of the bearing 
and a lubricator attached to feed oil to this groove, 
that even with a pressure of seven (7) inches head of 
oil, it would not feed to the bearing, but, on the con- 
trary, it appeared to be the means of escape for the 
film of oil between the bearing and the journal. When 
the cup lubricator was the only feeder, the bearing 
would not run cool with the pressure as low as 100 
pounds per square inch. In this case, care was taken to 
chamfer the edges of the groove to prevent any scrap- 
ing action. As the point of application of the lubricant 
was moved from a vertical towards a horizontal posi- 
tion, the friction decreased and the bearing was found 
capable of carrying greater pressure before seizure. The 
experiments by Tower to determine the pressures at 
different parts of the bearing are so indicative of the 
wedging action which takes place that they are referred 
to somewhat in detail. The bearing was divided into 
three (3) vertical planes lengthwise of the bearing, and 



METHODS OP LUBRICATION. 



39 



each half into three (3) planes at right angles to the 
first ones. 

The lubricator was placed on the intersection of the 
planes passing through No. o, No. i, and No. 2, and 



N6. Ni. 1' 'No. 2 



I No.8A,l<rojl. 



N^. 1 No. 2 




Fig. 5. 

the same pressures assumed for No. i A and No. 2 A 
— rather an unfortunate assumption, especially as the 
means of distribution may have had an effect upon the 
pressure at the points on the rear half of the bearing. 
The results were as follows : 



Longitudinal Planes. 


On. 


Centre. 


Off. 


Transverse Plane No. 0. . . . 
" No. I.... 
" No. 2.... 


370 
355 
310 


625 
615 
565 


500 
485 
430 



The figures represent in pounds the pressure per 
square inch. The bearing had a total load of 8008 
pounds, the journal running at a speed of 150 revolu- 
tions per minute. Temperature constant at 90° (Fahr.). 
Journal 4X6 inches. 

The maximum pressure was at the centre, as was to 
be expected ; but the increase on the off side of the bear- 



40 CAR LUBRICATION^. 

ing would go to indicate that the wedging action is so 
dominant as to actually skew the bearing on the jour- 
nal, and would do so where there is clearance between 
it and the sides of the box to allow of any such motion. 
That such results are shown by experiments, while in 
practice this method of lubricating from the top of the 
bearing is giving more or less satisfaction, can be attri- 
buted only to the effect of the end play of the bearing on 
the journal, and to the change in position when the bear- 
ing and journal are not as closely fitted as was the case 
with the apparatus which Mr. Tower used and which 
was probably necessary for the nature of the tests which 
he made. It then becomes apparent that the method of 
oiling from the under or exposed part of the journal is 
by no means the most inefificient one, but, on the other 
hand, seems to be the best way of introducing the 
lubricant. Inasmuch as the oil-bath method has been 
found impracticable, the result obtained by it is a favor- 
able indication that the use of waste placed under the 
journal as now practiced is capable of giving highly ef- 
ficient results. To obtain the very best effect in this 
way, however, it is necessary to observe a number of 
the details of the method. For instance, when using 
new waste it is important, in fact necessary, to thor- 
oughly saturate it before placing it in service, which 
will be clearly seen from the following experiment. 
With one road it was the practice to oil journal-boxes 
of passenger equipment cars at the end of each of the 
sub-divisions of a main line with the object of prevent- 
ing the occurrence of heated journals and assuring the 
condition of good lubrication. To test the necessity of 
this method a car was selected, the journal-boxes of 



METHODS OF LUBRICATION: 4 1 

which were carefully cleaned and repacked with new 
waste which had, for some few hours only, been thor- 
oughly soaked in oil. For some two hundred miles of 
the run after repacking, the journals were very warm 
and had almost reached the point where scaling of the 
surface of the bearing takes place. No oil was placed 
in the boxes, however, especially as it was found that 
the journals seemed to become cooler as the distance 
run was increased. The car was taken some four hun- 
dred and fifty (450) miles out, when the journals were 
very cool and reached their destination in good condi- 
tion. The car was returned to the starting point, and 
it afterwards made a second round trip, covering in all 
eighteen hundred (1800) miles with one oiling, and yet 
at the start it seemed as though the car would not suc- 
ceed in covering more than one hundred (100) miles be- 
fore trouble would arise. The warm condition of the 
journal and surrounding parts increased the fluidity of 
the oil and enabled the waste to more easily absorb it 
and exercise its capillarity. That the waste at the end 
of the second round trip was still in good condition 
partly indicates what can be accomplished by sys- 
tematic attention, although the trial does not indicate a 
successful but rather a dangerous way of saturating the 
waste. It is cited to emphasize the importance of hav- 
ing the waste well saturated before placing it in boxes. 
In a short paper read by the writer (see Proceedings 
of Engineers' Club of Philadelphia, fall of 1886) there 
is given the result of a crude experiment made with the 
object of roughly determining the absorptive powers 
of fibrous and woollen waste. A small quantity of dry 
woollen waste was taken, one end of which was placed 



42 CAR LUBRICATION. 

in a large cup half filled with oil, and the other end, 
after passing over the top of the cup, was allowed to 
pass down the outside and rest upon a table. After 
standing some twenty-four (24) hours, the waste was 
oily to the touch and a small oil-spot was found upon 
the table. The waste was allowed to remain in this 
condition for some two (2) or three (3) days, but 
seemed to absorb but little if any more of the oil, in- 
dicating the almost inappreciable effect of capillarity 
in comparison with what is already known as its ab- 
sorbtive power. When the best results are desired 
from this method of lubrication, the necessity of thor- 
oughly saturating the waste, that is, covering it with oil 
for some days before using, becomes apparent. The 
object should be to produce with waste, as near as can 
be obtained without incurring the loss resulting from 
splashing, the condition known as the oil-bath method 
of lubrication. To obtain such a result we cannot 
depend much upon the capillarity of the material. 
The condition to give this end is, it seems, to obtain a 
state of saturation such that the journal is continually 
replenished with oil as it revolves. The degree of 
saturation will decrease from that at the bottom of the 
box to the top of the waste. The top of the waste 
should contain an amount of oil just below the state, 
where it will run from the back or front of the box, 
hence the advisability of having these points as nearly 
oil-tight as practicable ; they not only reduce the loss 
of oil, but also render a lower resistance from friction. 
The small amount of dependence which can be placed 
upon capillarity can also be tested and proved by an 
examination of the waste of a journal-box which hag 



METHODS OF LUBRICATION. . 43 

been in service some months. That at the front will 
be found to be much better saturated with oil than the 
waste at the back of the box. For this reason it is 
thought the oil should be introduced into the box at 
some point about midway of the journal, which can 
be readily done by small openings in the front and 
leading back by cored passages to any point where it 
is desired to bring the oil in contact with the waste. 



44 CAR lubrication: 



CHAPTER VI. 

JOURNAL-BOX CONSTRUCTION. 

Many types of journal-boxes have been desig^ned, but 
ve/y few of these have carried all the essential features 
that go to make up a good, efficient journal-box. For 
instance, some have devoted all their attention to the 
construction of the rear end or dust-guard part of the 
box, while others to the front or lid, and so on. 

The distribution of the load, however, seems to have 
received less attention than any other feature. It is 
unnecessary to give a historical review here of the 
numerous devices which have been tried to make the 
box dust- and oil-tight ; but suffice it to say that effi- 
cient means to accomplish these results, especially for 
the back of the box, are too much overlooked. A good 
dust-guard seldom proves a bad investment ; it should, 
however, be simple in design and of a material that 
will not be affected by the oil. It should also accom- 
modate itself to any wear of the bearing. 

The method of distributing the weight upon the 
bearing is an interesting analysis, and, if not carefully 
followed, will produce results from which considerable 
trouble may arise. From the conditions of the case it 
will be well understood by those at all familiar with 
the design and nature of the mechanical appliances 
used for carrying the weights of cars that mechanical 
accuracy in the parts cannot be obtained. Especial 



JO URN A L-B OX CONS TR UCTION. 



45 



reference is made to the condition of the seat in the 
top of the box and the top of the bearing, both of 
which are rough castings, and, however, clean and 
accurate these may be in the rough, it is impossible to 
obtain a condition for the distribution of the load such 
as can properly be expected from finished surfaces. In 
one of the designs which has come under notice the 
weight was thrown on the centre of the bearing, as 
shown in Fig. 6. Notwithstanding the bearing-metal 




Fig 6. 



was as strong as any known to the trade for such pur- 
poses, the result of this design, after some years of ser- 
vice, gave positive and decided indications of hollow- 
worn journals, due to the springing of the metal at the 
ends, as would naturally follow from this method of 
distributing the load. Fig. 7 indicates the result, 
exaggerated, to which reference is made. It may be 
safely inferred that to obtain sufficient strength of the 
bearing to prevent the journal wearing hollow when the 
load is distributed in this way, would require a thick- 
ness of metal much greater than when the distribution 
is more even or uniform. Other objections to this in^ 



CAJ? LUBRICATIOX. 



crease of the weight of the bearing will be found in the 
chapter on the Cost of Lubrication. 

The prevailing practice in the distiibution of the 
load upon the journal is that shown in Fig. 8, where, in 




Fig. 7. 

theor}% the weight is uniformly distributed over the 
whole top surface of the bearing. In practice, how- 
ever, the result is quite different from this, as will be 
readily seen by an examination of journals which have 
been used with this design of box. Instead of a uni- 




FiG. 8. 



form wear, it will be frequently, if not generally, found 
that the journal is worn small either toward the inside 
cr outside end, showing conclusively that most of the 
weight is thrown in either of these two directions. An 
analvsis of the conditions will give sufficient cause for 



JOURNAL-BOX CONSTRUCTION. 



47 



this result. The design indicated by Fig. 8 is that used 
by a number of the railroads, and is probably more 
favored than any other construction of journal-box. 
When all goes well uniform wear of the journal can 




Fig. g. 

be safely looked for ; but when considering that the top 
of the bearing is an unfinished casting, it is not surpris- 
ing to find the load actually taken as illustrated by 
Figs. 9 and lo ; the conditions shown in Fig. 9 illus- 
trating the effect of irregularly distributed high spots. 




Fig. 10. 

That shown in Fig. 10 may arise from one or two 
causes : ist. When the top surface of the journal-box 
is not parallel with the plane of the top of the bearing 
and the desired line of contact. This may arise from 
bad alignment of the box or lack of parallelism in the 



48 CAR LUBRICATION. 

rough castings. 2d. From a journal worn small at the 
front end. It is evident that the positive prevention of 
the first of these two causes would require a grade of 
refinement which present practice cannot meet. 

When considering Fig. 9 it should be remembered 
that three (3) points determine a plane, the exaggerated 
roughness of the top of the bearing indicating a possi- 
ble if not a probable condition. As the bearing is held 
during the boring by the top surface and the bottom 
edges, it is best, with this method of distributing the 
load, to roughly dress these edges, a, a, making them as 
nearly parallel with the surface b as possible, so that 
the bored part will be parallel with the top. 

The defective distribution of the weight arising from 
lack of good alignment, and particularly irregularities 
in the rough castings, can, of course, be partly overcome 
by finishing the fitting parts, but involving thereby aa 
expense which the conditions of the case would hard»ly 
warrant. It would seem, however, that by the method 
indicated in Fig. 11 the trouble would be alleviated 
without any increase in the refinement of the fitting 
parts. It will be noticed that provision is made to ac- 
commodate and meet the two prevailing objections to 
a good distribution of the load, and by finishing the 
edges, a, a, parallel with the top surface — the grinding 
of which is quite sufficient, — a more uniform equaliza- 
tion of the load can be obtained, and maintained with 
whatever changes may take place in the position of the 
box. It is seen that the bearing is loaded similarly 
to the method shown in Fig. 6, excepting that the 
free ends of the bearing are of less than half the 
length, and would not cause sufficient unequal wear of 



JOURNAL-BOX COMsTRUCTIOM. 



49 



the journal to prove a practical objection. It should 
be ren:iembered that the deflection of a beam varies as 
the cube of the length. When carrying the load in this 
way it is not at all necessary that the top of the bear- 
ing should be parallel with the top line of the journal. 
Stress has been placed on the method of distributing 
the load, and it is very apparent that it is much in- 
fluenced by the device used for transmitting the weight 
to the journal. Its effect is quite apparent in increas- 
ing the pressure per square inch on a small part of the 
journal, necessitating the use of an oil of higher resist- 



^^^^^ 



§^^^ 




Fig. II. 

ance than might otherwise be used. More than this, 
the effect is to wear the journal unequally, and in that 
way render it unfit to receive a properly prepared bear- 
ing when it is necessary to renew one. As regards the 
latter objection, if the bearing and journal were of 
equal life, and considering only the condition after the 
brass had worn to sufficient bearing surface to carry the 
load without excessive abrasion and resulting heating, 
it would be of less importance as to how the weight 
was distributed ; but when the journal, on an average, 
outwears some half dozen or more bearings, it becomes 



50 CAR LUBRICATIOM. 

correspondingly difficult to renew the bearings without 
encountering considerable annoyance from the condi- 
tion into which the journal has been worn by a load 
that has not been properly distributed. It is hardly 
strange that under such conditions delays from, and ex- 
pense of, hot journals are encountered. It is rather 
surprising that there is so little trouble. 

With the object of meeting these mechanical defects, 
Hopkins applied a lining of soft metals, generally lead, 
to the under side of the bearing, by which it can adjust 
itself to unequally-worn journals, and thereby render a 
larger surface for the weight than can be obtained when 
a more rigid metal is placed upon the journal. The ar- 
rangement, though patented at the time, was a most 
excellent one, and has given admirable results when 
properly applied to the bearing. It also assists in 
meeting the decrease in bearing-surface, which arises 
when a new bearing is placed upon a much-worn jour- 
nal. Care should be taken, however, to obtain the 
proper thickness of the soft metal lining which has 
been found to be about J^ of an inch. When more 
than this is used the lead is forced out at the edges of 
the bearing, and prevents the oil getting between the 
surfaces, and in other ways produces trouble. 

As the Hopkins patent has expired, a description of 
the way in which the lining is done may prove of 
value to those who are anticipating the lining of bear- 
ings. 

The operation is as follows: The bearings are first 
bored. As they are to be treated for lining, they are 
first placed on a coke-fire and allowed to become weU 
heated, when they are cleaned with muriatic acid and 



JOURNAL-BOX CONSTRUCTION. 



51 



tinned. They must then be warmed again so that the 
tin is in a condition for the lead to adhere to it. They 
are then placed on a mandrel to receive the lining of 
lead. The device for holding the bearings during the 
lining can be made of very simple construction. It 
should be so designed that the bearing can be clamped 
only centrally with the mandrel, which will make the 
lining of uniform thickness over the bearing. The 
radius of the mandrel should never be more than -^-^ to 
yi^ of an inch of the radius of the journal which the 
bearing is to fit. The lead lining should never, how- 
ever, be more than -^-^ of an inch thick ; and to insure 
this result, the mandrel for the particular diameter 
should be such as to prevent more than this amount 
between it and the bearing. The quantities of 
materials to line bearings with lead, at the present 
market prices, are as follows : 

TO LINE ONE HUNDRED (100) BEARINGS. 



Material. 


Amount 

in 
Pounds. 


Cost 

in 
Cents. 


Lead. . . 

Lead and tin for " tinning " (half-and-half) 

Muriatic acid 


60 

4 
0.4 


285.0 

70.0 

5 







The labor should not amount to more than two or 
three cents per bearing, as it does not require much 
skill for this work. 

The value of this lining as a bearing metal has been 
stated at figures, both high and low, but no reliable 
definite figures are at hand. 

As a soft metal, however, it will give excellent wear, 
which point has already been brought to notice in the 
chapter on Bearing Metal. 



52 CAR LUBRICATION. 



CHAPTER VII. 

COST OF LUBRICATION. 

The representation of journal friction in actual dol- 
lars and cents is, after all, the important part of the 
question of car lubrication. It forms the goal to which 
the results of all the investigations in this branch are 
directed. The question is as to how many additional 
cars will an engine haul, or what reduction can be 
anticipated by the introduction of a new device, or a 
definite grade of oil, or, perhaps, a particular alloy for 
the bearing metal, in the cost of maintaining, satisfac- 
torily, the lubrication of car journals. The efificiency 
cannot always, however, be seen in actual dollars and 
cents, without considering all the departments that are 
influenced. It is sometimes obtained through the re- 
duction of anxiety of those in charge, by a lessening of 
the number of delays to trains, as well as a question 
of accommodation of the patrons. Considerable an- 
noyance arises from heated journals, which are known 
to be expensive items of economy, if such can be, and 
is a true representation, when resulting from the use of 
ill-adapted or cheap material, or even of the design, of 
a small first saving with a large final expenditure. 

Included in the cost of lubricating car journals, as 
now practiced, is the wear of the bearing metal, 



COST OF LUBRICATION. 53 

quality and quantity of materials used in applying the 
lubricant to the journal, the cost and amount of the 
lubricant, the wear of the journal, and, still more im- 
portant, the cost of the resistance of friction as repre- 
sented in coal consumption. Many of these variables 
are dependent upon the relative location of the line of 
the road to the supply markets, as also the current 
market prices of the articles needed, the importance of 
which is not to be considered here, but rather that of 
the efficiency of the mechanical parts. A combination 
of all these elements is obtainable, giving the cost of 
maintaining properly lubricated car journals. This is 
also reducible to a condition representing the actual 
economy of oils of different quality and price, which is 
varied and experimented with probably more than any 
other single one connected with the subject — probably, 
too, because it is the easiest to handle. 
To obtain an expression for the cost, let 
B = abrasion in ounces of metal per journal per looo 

miles run ; 
d = cost of bearing metal per ounce ; 
O = quantity of oil in pounds consumed per journal 

per 1000 miles run ; 
o = cost of oil per pound ; 
W= quantity of waste consumed in pounds per 

journal per lOOO miles ; 
w = cost of waste per pound ; 
C = coal required expressed in tons per horse-power 

developed ; 
c = cost of coal per ton ; 

A = wear of axle, diametrically, in decimals of an 
inch per looo miles run 



54 CAH LUBRICATION. 

a = cost of axle wear, including the item of labor 

for finishing, per looo miles ; 
J =: journal resistance in pounds per ton of load; 
T = load in tons per journal ; 
d = diameter of journal in inches ; 
d' = diameter of wheel in inches. 
The horse-power developed due to journal resistance 

would then be, per journal per lOOO miles 

run, 

1000 ^djY.TY. 5280 , 

—p^— X ~F X = horse-power. 

60 a 33000 ^ 

The cost of lubricating one journal, including the 
cost of overcoming friction, would be represented by 
the expression 

2.667 -, . CcJT^ Bb -\- Oo -}- Aa ^ Ww = M. 

If it is desired to compare two oils, there is but one 
item, that of the value of the waste, which can be left 
out of consideration. All the other functions enter as 
elements of the cost. The axle and bearing wear 
differs but little with two oils, unless there is con- 
siderable difference in their lubricating powers, so 
that, for comparison, the expression could safely be 
reduced to 

M_ 2.66yCc/T-{-Oo 

M ~ 2.667C'c'/'T-\- O'o" 

by which the relative value of two oils, M and M\ 
can be determined. The object is to give, approxi- 
mately, the values of the several functions entering as 
elements of cost of lubrication, and from them to obtain 



COST OF LUBRICATION. 55 

some idea of the amount of this item when based on 
what. is considered as average practice. 

The coal consumption is determinable through the 
pounds resistance offered by the friction of the journal. 
It should be remembered, though, that it is pounds of 
traction, and when determining the coal consumed it 
should include the losses which take place between the 
boiler and the rear coupling of the tender. It is un- 
fortunate that there is such a wide difference of opinion 
as to the pounds of resistance due to journal friction, 
a variation which can be accounted for only by the 
differences in the methods adopted by the various 
roads of lubricating journals and the nature of the tests. 
A close approximation for average service can be 
assumed, and a comparison can be made of the differ- 
ence which would result from about as wide a variation 
in the conditions as is found in practice. Many people 
use the resistances that have been obtained from 
laboratory tests, but these do not give as close an 
approximation to the practical conditions as those 
derived from accurate dynamometer readings. The 
latest dynamometer diagrams show, with an engine of 
the consolidation type and with cars of 6o,ooo pounds 
capacity when running on a level tangent at a constant 
speed of fifteen (15) miles per hour, a resistance of 2\ 
pounds per ton. This was with a heavy freight train, 
and the resistance would probably rise to 3^^ pounds 
per ton for lighter trains. Assuming the weight of the 
average freight train in the United States as 130 tons 
gives a basis from which an average figure can be 
obtained of the cost of overcoming journal resistance. 
With an average car-load of 15 tons this would give 8f 



56 CAR LUBRICATION. 

cars per train of 130 tons. With cars having eight 
journals, this gives the load per journal of 3750 pounds. 
With 3 pounds resistance per ton would require, from 
page 54, 1.82 horse-power per 1000 miles run. This is 
for each journal, while the loss between the engine and 
the rear end of tender would be about 30 per cent, 
which would increase the power, when figured for the 
cost at the boiler, to 2.6 horse-power. With coal at 
$1.50 per ton on the engine, and a consumption of 4f 
pounds per horse-power, gives as average cost for the 
frictional resistance per journal per lOOO miles 0.926 
cent. For comparison, let it be assumed that the oil 
selected is ill adapted to the purpose, as, for instance, 
that the conditions of the service are such that an oil 
of a resistance of 0.512 pound per square inch would 
be sufificient to meet the requirements, but in its stead 
one with a resistance of 0.652 pound per square inch 
had been previously selected and used. The cost per 
journal would then be 1.20 cents, representing an in- 
crease of over 29 per cent, indicating at once the 
advisability of selecting that oil which will give the 
least resistance, but which is, at the same time, capable 
of withstanding the maximum pressure. 

Considerable variation will be found in the oil con- 
sumption, depending on the nature of the service. 
With passenger trains the high speed requires a more 
thorough oiling to dissipate the large amount of heat 
generated by the resistance of friction. In this case 
the heat must be carried ofT much more rapidly than 
in freight service, where any surplus heating by friction, 
arising from grit or other foreign matter, has more time 
in which to allow the journal to cool before reaching 



COST OF LUBRICATION. 57 

that state where the bearing and journal seize. In 
passenger cars the effect is quite different and requires 
means for absorbing in as rapid a manner as possible 
any surplus heat generated. It would then seem that 
the difference in the consumption of oil in the two 
cases has arisen, not from a desire or necessity to 
reduce the coal consumption, but rather to prevent the 
annoyance arising from hot boxes ; but when this 
annoyance has been reduced, it is too often assumed 
that the ideal condition of lubrication has been ob- 
tained. For instance, the oil consumption for passenger 
service has been known to be as high as 2.1 pounds 
per journal per 1000 miles, and as low, in the same ser- 
vice, as 0.55 pound. The first is an average condition, 
while the second is the case of a car that was being 
followed to compare the best results of woollen waste 
against a patented device, and indicates the possibilities 
in the way of oil consumption where closer attention 
or more systematic means are applied for lubrication. 
To further indicate the variation in oil consumption 
upon different roads, two lines were compared where 
the conditions of the service were as nearly equal as 
could be desired for a comparison. The oil consump- 
tion per journal per 1000 miles was, upon one, 0.354 
pound and, upon the other, 1.05 pounds. From this, 
the difficulty of obtaining an average figure will be 
understood. We will, for an example and an approx- 
imation, assume it as one (i) pound per journal per 
1000 miles in passenger service, and as 0.37 pound for 
freight cars. In the ratio of their relative mileages, 
this would give an average consumption of 0.5 pound 
of oil per journal per 1000 miles. At 2^ cents per 



58 CAR LUBRICATION. 

pound, 1.25 cents would represent the value of the oil 
consumption. 

When considering the question of bearings, attention 
is drawn to a very pretty point of economy. It is a 
point that is generally overlooked, while it affects quite 
as much the cost of the bearing as that of the metal 
abraded. It will be noticed that bearings are removed 
from service for two general reasons : first, where they 
are defective from overheating, or where they have 
become too thin from wear ; second, from such other 
defects as require the removal of the axle. The second 
includes defective wheels, etc. In the first case the 
bearings are fit for scrap but nothing better, while 
under the second heading the bearings may be com- 
paratively new or but partly worn out. In fact, it will 
be found by an examination of a number of bearings 
removed from service, especially where the hard metals 
are used, that an average life of the bearings would 
not give more than from one half to two thirds their 
total wearing thickness as having been abraded before 
removal. The weight of metal remaining is seldom fit 
for further service, so that the loss, representing the 
difference between the first and the scrap value of the 
remaining part, must enter as an element of the cost 
of the abraded metal. For example, taking a bearing 
which costs to produce, labor and material, 16 cents 
per pound and weighing 10 pounds, represents as the 
total value of the bearing $1.60. To compare extreme 
conditions, if two ounces are worn away in one case 
and eight pounds in the other, the value of the abraded 
metal, rating the scrap as one half the original value, 
would be as follows : where two ounces is abraded, the 



COST OF LUBRICATION. 59 

value of abraded metal at $6.48 per pound, and where 
the eight pounds is worn away, a cost of 18 cents per 
pound. The latter would also give a greater average 
mileage per ounce of wear, as this becomes less rapid 
as the bearing is better seated to the journal. This is 
an extreme case, however, and in the absence of positive 
information we can safely assume, for approximate 
figures, the average condition as that where the bearing 
has worn fifty (50) per cent of its total weight. The 
first weight will be assumed as ten (10) pounds at a 
cost of sixteen (16) cents per pound. This gives the 
ounce value of the abraded metal as 1.5 cents. The 
wear per journal per 1000 miles is about 0.75 ounce, 
the value of which would be, on this basis, 1.12 cents. 
Objection may be raised to the rather low percentage 
of wear which is taken as the amount of abrasion of 
the bearing before removal from service, but an 
examination of the bearings that have been taken from 
cars and scrapped will show that they do not reach as 
high a percentage of wear as this, especially with the 
harder metals which is not due to any lower percentage 
of abrasion so much as to the more frequent removal 
from heating and similar causes. Take, for instance, the 
practice of using a cast-iron shell and filling it with a 
soft or so-called white metal. To eliminate the differ- 
ence in the cost of the metal used for abrasion they 
will be assumed as of the same value, but instead of 
the bearing containing ten (10) pounds we will take it 
as consisting of seven (7) pounds of abrading metal, 
five (5) pounds of which, as with the solid bearings, is 
assumed as worn away before removal. The value of 
the abraded white metal would be 1.2 cents per ounce, 



6o CAJ? LUBRICATION. 

and for the hard metal, as before, 1.5 cents per ounce. 
The cast-iron shells are practically indestructible. The 
cost of refilling a shell with soft metal would be less 
than the expense of moulding the hard metal in sand. 
To go still further, let it be assumed that both bearings, 
as ready for service, are of the same weight, and that 
the cast-iron shell of the one weighs three (3) pounds. 
Assuming the same weight added to the hard metal 
for strength, this would represent, with cast iron at twa 
cents per pound and for an equipment of 50,000 cars, 
an increased capitalization of $168,000 more than where 
the cast-iron shells and white metal are used. It 
should be understood that this represents the increased 
outlay which is necessary for equipping with the hard 
metal bearings, but does not include the reduction of 
the value of the abraded metal, nor the less cost of 
preparing the shell with soft metal bearing. It is 
figured on a conservative basis. A more detailed 
comparison of the two kinds of bearings would show 
still further in favor of the soft metal, and the argu- 
ment would indicate the advisability of such for car 
service. The so-called wedge or liner which is used 
over the top of the bearing in the Master Car-builder's 
design of box may be considered a step in this direc- 
tion. 

The wear of axles will depend much upon the ser- 
vice, whether used under passenger or under freight 
cars ; but when the axles are made of steel, and with 
wheels 33 inches in diameter, the wear is found to be 
about 0.0014 of an inch per 1000 miles. This figure is 
an average of a number of axles under passenger- 
equipment cars. Axles weigh some 375 pounds when 



COST OF lubrication: 6i 

new, which, at a cost of 2 cents per pound, would be 
$7.50. Adding to this the labor of turning and pre- 
paring for service would make the first cost about $8.50. 
With an allowable diametrical wear or a diametrical 
reduction of one half (|-) an inch reduces the weight of 
4X8 journals fifteen (15) pounds, and a scrap rate of 
one-half a cent per pound would give the value of the 
axle wear per journal per 1000 miles as 1.877 cents. 

The quantity of waste required per journal-box is 
about 1.349 pounds, from which an approximate 
average of 30,000 miles is obtained, representing, at 8|- 
cents per pound, i \\ cents as the value of this material, 
to which should be added the cost of the oil used in 
saturating the waste, as this is generally thrown away 
with the waste when the latter is removed. The 
amount of oil necessary to saturate the waste for one 
box is 8.4 pounds, which, at a rate of 2\ cents, would 
make the total for the waste and the oil 32^^ cents, or 
1.083 cents per journal per 1000 miles. 

To summarize we find as follows : 



Per Journal per looo Miles. 



Coal required in overcoming journal friction. 

Lubricant 

Bearing metal , 

Axle wear , 

Waste and oil used in packing boxes 

Total 



Cost in Cents. 



0.926 
1,250 
1. 120 

1.877 
1.083 



5.751 



It should be remembered that the coefficient of fric- 
tion and the consequent coal consumption are dependent 
upon the nature of the service, and will be affected by a 
number of elements, such as the load carried, the nature 



6^ CAR luSricatioi^. 

of the bearing metal, and the oil, together with other 
minor influences which have been mentioned under their 
respective headings. So, too, the item representing the 
oil consumption is dependent upon the grade of such 
material, as well as the amount which, in the judgment 
of the person in charge, is considered necessary for good 
lubrication ; and is also influenced, to a large extent, by 
the design and maintenance of the journal-box. 

Lately there has been a tendency to substitute a 36- 
inch wheel for those 33 inches in diameter, especially 
in passenger service. The small additional cost, all of 
which is included in the increased weight of iron, is 
more than balanced by the less wear and tear of the 
wheel, resulting from a less number of revolutions, so 
that the work of friction can be considered as reduced 
to an extent equivalent to the proportionate increase 
in diameter. This would affect the coal consumption, 
together with the wear of the bearing and axle, in each 
of which a proportionate decrease can be looked for. 



Per Journal per looo Miles. — Wheels 36 inches diameter. 



Cost in Cents. 



Coal consumed in overcoming journal friction. 

Lubricant 

Bearing metal 

Axle wear 

Waste and oil used in packing boxes 

Total 



0.849 

1.250 

1.027 

1.72 

1.083 



5.467 



As regards lubrication, the 36-inch wheel is 5 per 
cent cheaper than one of 33 inches diameter. 



HEATED jOUR^AL^. 6^ 



CHAPTER VIII. 

HEATED JOURNALS. 

If a journal becomes overheated, it is positive indi- 
cation that some part of the mechanism is out of order, 
just as with the human body any sickness is proof 
positive that one or other of the organs is not perform- 
ing its proper function. The moral effect in the two 
cases is also similar; for no one points with pride, un- 
less it be on a competitive line, to a car that is passing 
and leaving behind it a streak of red flame and heavy 
obnoxious smoke from one or more journals, that have 
become hot. 

It occasionally happens, and but occasionally, that 
journal-boxes receive too much care. This is apt to 
arise with trains in heavy service and in which delays 
attract unusual attention. With such trains it has 
been known that too much care has been used in the 
attention given to the boxes, especially in the too 
frequent use of new waste. 

The examination of a bearing that has been removed 
from an overheated journal will seldom give suf^cient 
trace of the cause. No attention should be given to 
the scaling found on such bearings, as it is simply a 
result and seldom indicates anything more than that 
the bearing has been in contact with the journal and 
heated by the friction so produced until the scaling 
resulted. 



64 CAR LUBRICATION^, 

The cause of most of the hot boxes can be reduced 
to two general headings, 

1st. Those produced by mechanical defects. 

2d. Those due to defective lubrication. 

The first is of such a nature that the construction 
can generally be analyzed and corrected. It may be 
in the design, such as the method of distributing the 
load, or imperfect protection from dust and oil. Or it 
may arise from poor quality of bearing metal, waste, or 
oil. These as such require the proper course for their 
elimination, although a slow process, and sometimes 
an expensive one, especially when it becomes necessary 
to change the design of the box and the size of journal, 
etc. It sometimes occurs that the trouble can be 
obviated by the use of some mechanical turn, such as 
using a lead lining where the load is not well distributed. 
One case is known where a re-designed journal-box 
which became necessary from more severe service gave 
a remarkable reduction of heated journals. The per- 
centage of old and new journal-boxes in service was 
about in the ratio of four (4) to one (i) ; while the 
number of heated journals arriving at a specified point 
within a given length of time gave the respective ratio 
of one hundred (100) to three (3), before and after the 
change was made in the box. The cars having the 
newly designed box with large journal were placed 
in the heaviest and most severe service. 

Heated journals have been known to have occurred 
from a steady and heavy application of the brakes, re- 
ferring to those applied by compressed air. When 
tracing this cause of heating it has been found that a 
new bearing, or one the radius of which is consideraoly 



HEATED JOURNALS. 65 

larger than that of the journal, was used, and the 
amount of clearances between the pedestal and the 
journal-box, was greater than that between the sides of 
the bearing and the box, so that a slight raising of the 
bearing resulted from the box pressing heavily upon 
one side of the bearing. In this way, the edge of the 
bearing is thrown against the journal, when all the 
pressure is taken by a very small area ; and, if the 
brakes are kept on for sufficient time, more or less 
heating, but not always a severe condition, will result. 
It is not uncommon for heating to occur from the long 
fibres of new waste working between the bearing and 
journal, and especially before the bearing has worn 
down to its whole arc of contact. 

Under the second head are included those caused 
by the use of poor quality of oil or waste and those 
that are due to improper attention. These arise from 
the lack of sufficient oil for lubrication, but more par- 
ticularly where the waste next the journal has become 
so deteriorated from foreign matter as to prevent good 
lubrication. The pasty condition of the top of the 
waste, more particularly where the animal oils are used 
is due also to their oxidation and their effect upon the 
bearing metals, the extent of which was indicated in 
the chapter on Bearing Metals. 

The preventive for heated journals, coming under 
the second heading, would be a systematic method 
of attending to the lubrication. By this is meant that 
after the car had made a specified mileage, remove the 
waste from the boxes, which, instead of being thrown 
away, can be cleaned and thoroughly saturated with 
oil, when it will be ready to be again placed in boxes 



66 CAR LUBRICATION. 

for lubrication. The important point is to break up 
the hard, gunrimy surface which forms on the top of 
the waste, and this can only be accomplished b)'' re- 
moving the waste from the box. It is probably safe to 
say that the method of attending to the lubrication of 
car journals on most if not all of the railroads of the 
country to-day is about as follows. The boxes are 
packed and oiled when the car first leaves the shop. 
After it is in service it is occasionally, or it may be 
frequently, oiled ; by which is meant the front of the 
box is opened and a small amount of oil is poured in 
upon the top of the waste at the front. The box is 
allowed to run in this way, with the little additions of 
oil, until it is removed either for the renewal of a worn 
bearing, changing the wheels, or for a heated journal. 
The top of the waste in the mean time has become 
saturated with foreign matter, making a pasty condition 
which is aggravated where the animal oils are used on 
account of their oxidation, and probably more or less 
from the action of the acids upon the bearing metal. 
This condition of the top of the waste not only acts as 
a poor lubricant next to the journal, but prevents the 
oil at the bottom of the box from reaching the journal. 
Of the fresh oil poured into the box from time to time,' 
a small part is retained by the waste, but a hastif' 
examination will indicate that a large part is lost and 
thrown upon the ties. It has often been thought that 
a systematic method of removing the waste, so as to 
break this hard or pasty surface, would prove a very 
profitable investment. If the waste, after cleaning, 
contains too much grit or foreign matter to prevent its 
further use, let the oil, which in car service is never 



HEATED JOURNALS, 6/ 

what is called worn out, be extracted from the waste 
and re-used, thoroughly cleaning it and straining to 
remove foreign matter. 

Until more uniformity in the design of journal-box 
and handling of freight cars can be obtained than now 
exists, the above would, of course, apply only to 
passenger-equipment cars. 

It should be remembered that poor lubrication is 
represented in cost by actual dollars and cents, the 
extent of which is shown in the chapter on Cost of 
Lubrication. 

Like many troubles, a large percentage of the hot 
boxes could be prevented by the proper application of 
a handful of oil, provided such is done before the sur- 
faces of the bearing or journal have become injured. 

The present method of lubricating car journals is by 
no means an imperfect one when the best is made of 
it, and we should be careful not to attribute the failures 
arising from a lack of proper attention to the method. 



APPENDIX. 



EXPERIMENTS ON THE LUBRICATION OF 
AXLE-BEARINGS. 

By E. Chabal, in Revue Ge'n/rale des Chemins de Fer. 

From 1871, the period at which the Paris-Lyons- 
Mediterranean Railway Company abandoned grease 
for lubrication for the axles of carriages and wagons, 
and adopted oil, they, up to 1885, had made use of 
bronze bearings and of colza-oil (pure in summer, with 
an addition of 10 per cent of shale-oil in winter). 

In 1885 the trials made by other companies in the 
use of white-metal bearings and mineral oils induced 
them to make similar experiments, and also to find out 
whether the substitution of wool for cotton for the 
lubricating wicks would not be advantageous. They 
consequently made a series of tests to compare the 
results of using (i) white-metal bearings lubricated with 
mineral oil, (2) bronze bearings with mineral oil, and 
(3) bronze bearings with colza-oil. 

The following is a resume of the tests made : 

A. Tests made from 1886 to 1889, ^^ measure di- 
rectly the resistance of wagons to traction by means of 
allowing them to gravitate down a gradient and meas- 

69 



70 APPENDIX. 

uring the time taken. These tests have enabled the 
following to be compared : 

1. The resistances of wagons having different kinds 
of bearings with different lubricating-oils. 

2. The resistances of two wagons coupled together 
and one running alone. 

3. The resistances of open and covered wagons. 

4. The resistances of wagons on two axles and on 
three axles. 

B. Tests made from 1889 ^^ 1890, to measure di- 
rectly the resistances of wagons to traction, in drawing 
coal-trains divided into two parts of 300 tons each ; 
this division is made only for the purpose of comparing 
the influences on the two parts, and measuring the re- 
sistance of each by means of two dynamometer cars, 
and thus also enabling the resistances of wagons placed 
at the head of a train to be compared with those at the 
rear. 

C. Abstracts made from 1887 to 1889 on a certain 
number of carriages running in service with bearings 
made of pure metal and bronze, giving the mileage run 
over. 

D. Abstracts made in 1891 of the consumption of 
oil on passenger trains mounted on bearings of pure 
metal, and lubricated (i) with colza-oil, (2) with min- 
eral oil. 

E. Tests made in 1891 to determine the capillarity 
of the staple for lubricating-wicks, whether they be of 
wool or cotton, and according to what oil is employed. 

F. Tests made from 1888 to 1891 on carriages in 
service, to compare the lubricating-wicks of cotton and 
wool. 



APPENDIX. yi 

G. Tests made in 1890 on vehicles running by them- 
selves with two and three axles. 

The following is a summary of the conclusions ar- 
rived at : 

LUBRICATING-WICKS. — The tests made to compare 
the woollen wicks with those of cotton in regard to the 
facility with which they supply the oil have shown a 
superiority of delivery of from 50 per cent to 100 per 
cent in favor of the woollen wicks. It was also found 
that the renewals of the woollen wicks were only 68 in 
number compared to 100 of the cotton ones, and that 
the woollen wicks were less liable to firing. Notwith- 
standing the higher price of the woollen wicks, it was 
found economical to use them, and since May, 1893, 
the Paris-Lyons-Mediterranean Company have adopted 
them entirely. 

Bearings. — The result of the tests made showed 
that the wear of white-metal bearings was 50 per cent 
less than in the case of bronze bearings. The tests 
also showed that, by the use of white-metal bearings, 
a diminution of 20 per cent on the resistance of fully- 
loaded coal-wagons, forming trains weighing 300 tons, 
travelling at speeds of 16 miles to 26 miles an hour, 
was given ; that, as the speed increased, this gain was 
diminished, but remained always 5 per cent less. As 
a consequence of these tests, the Paris- Lyons-Mediter- 
ranean Company in 1893 abandoned the use of bronze 
bearings for carriages and wagons, and adopted white- 
metal bearings. 

Lubricants. — The tests made by abandoning car- 
riages to themselves on a gradient have fully justified 
the rejection by nearly all the railway companies of 



J 2 APPENDIX. 

grease and the adoption of oil. Grease gave, for car- 
riages isolated and mounted on bronze bearings, an 
increase of resistance per ton of : 
^ 25 per cent in comparison to mineral oil at low 

speeds (19 miles an hour) ; 
40 per cent in comparison to colza-oil at low speeds 

(19 miles an hour) ; 
3 per cent in comparison to mineral oil at high 

speeds (38 miles an hour) ; 
14 per cent in comparison to colza-oil at high speeds 

(38 miles an hour) ; 
The increase of resistance would be greater in ordi- 
nary trains than indicated above for isolated carriages. 
From these same tests, combined with those made by 
means of the dynamometer-cars, it was found, in com- 
paring colza-oil, mineral oil, and mixtures of these two, 
that colza-oil is more advantageous than mineral oil, 
and that the mixtures are classed between the two. 
Taking white-metal bearings, colza-oil, with an addition 
of 10 per cent of shale-oil, appeared to be very nearly 
equal to pure colza-oil in relation to non-resistance to 
traction ; pure mineral oil gave in relation to pure colza- 
oil an increase of resistance per ton of 15 per cent for 
trains of 300 tons, composed of fully-loaded coal- 
wagons, and running at speeds of 16 miles to 26 miles 
an hour. The mixtures of mineral and colza-oil gave 
more resistance than pure colza-oil, and the increase of 
resistances were, in the same trains : 

13 per cent for the mixture of 75 per cent of mineral 

oil and 25 per cent of colza-oil ; 
7 per cent for the mixture of 50 per cent of mineral 

oil and 50 per cent of colza-oil ; 



' APPENDIX. 73 

3 per cent for the mixture of 25 per cent of mineral 
oil and 75 per cent of colza oH. 
It was also found that in summer the consumption 
of colza-oil was only 0.8 of that of mineral oil. The 
tests were not made in winter, but it is presumed that 
then the consumption of mineral oil would be less. 
As a result of the tests, the Paris-Lyons-Mediterranean 
Company abandoned in 1891 the use of mineral oil, 
and adopted exclusively colza-oil with an addition of 
10 per cent of shale-oil, the latter having the advantage 
of thickening less at a low temperature. The author 
estimates that in round numbers his company spent in 
1890 ;^640,000 in coal for the traction of their trains, 
and used J^d tons of lubricants. If mineral oil had 
been used in place of colza-oil, ;^64,ooo more would 
have been expended on coal and ^^12,250 less on oil, 
thus justifying on the side of economy the choice of 
colza-oil. 









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